The present invention relates to black composite particles for semiconductor sealing material and a semiconductor sealing material using the same, and more particularly, to black composite particles for semiconductor sealing material, which are not only enhanced in blackness, moisture resistance, fluidity and tinting strength, but also show an excellent dispersibility in binder resins, and a semiconductor sealing material capable of exhibiting a high volume resistivity as well as excellent blackness, moisture resistance, soldering heat resistance, flowability and flexural strength (rigidity) by using the black composite particles.
In order to physically and chemically protect and fix electronic parts such as IC, LSI, transistors, thyristers and diodes, there are conventionally known so-called resin sealing techniques for sealing these electronic parts with thermosetting plastic resins.
With the recent development of large-scale sealed plastic packages, silica particles are added as a filler to semiconductor sealing materials in order to enhance a mechanical strength thereof.
However, it is also known that the silica particles have silanol (Si—OH) groups on the surface thereof and, therefore tend to show a high water absorption property due to hydrogen bonds of the silanol groups.
Since the plastic packages are exposed to an elevated temperature as high as not less than 200° C. during a soldering step when mounted on printed wiring boards, there arise problems such as formation of cracks in the packages and formation of gaps on the surface of Si chips due to vaporization of water absorbed therein under high temperature condition.
On the other hand, it is required that the plastic packages show a black color for rendering the packages light-non-transmittable. For this purpose, carbon black is usually used as a colorant. However, the carbon black tends to be self-agglomerated because of fine particles having an primary average particle diameter as small as about 0.005 to 0.05 μm, so that it may be difficult to disperse the carbon black in the form of fine particles in resin compositions. In addition, it is known that the agglomerated carbon black is in the form of coarse particles having a maximum particle diameter of usually 0.1 μm to 5 mm. When applied to semiconductor sealing materials, the agglomerated carbon black tends to cause clogging between the printed wiring patterns, resulting in defects such as leak. Further, since the carbon black particles are bulky particles having a bulk density of about 0.1 g/cm3 and, therefore, tend to be deteriorated in handling property and workability. Furthermore, since the carbon black particles themselves are a conductive material, it may be difficult to add a large amount of carbon black particles to the semiconductor sealing material requiring a high insulating property.
For these reasons, it has been required to improve various properties of the semiconductor sealing materials, such as a moisture resistance, a blackness, an electrical resistance and a mechanical strength, by developing new silica particles as filler.
In addition, it is demanded to provide semiconductor sealing materials having a good flowability upon molding.
At present, in order to enhance a compatibility with binder resins, there are known techniques for treating the surface of the silica particles with a silane coupling agent or silicone oil (Japanese Patent Application Laid-Open (KOKAI) Nos. 8-245835(1996) and 10-279667(1998), etc.); techniques for previously heating the silica particles in a temperature range of 100 to 1,000° C. and then treating the thus pre-heated silica particles with silane coupling agent in order to reduce the amount of silanol groups on the surface of the silica particles (Japanese Patent Application Laid-Open (KOKAI) No. 11-43320(1999)); and techniques for controlling the maximum particle diameter of carbon black or silica particles added to resin compositions (Japanese Patent Application Laid-Open (KOKAI) Nos. 2001-19833, 2001-69268, 2001-247747 and 2001-329146).
At present, it has been strongly required to provide black particles for semiconductor sealing material, which can exhibit not only excellent moisture resistance, blackness, fluidity and tinting strength, but also excellent dispersibility in binder resins. However, the conventional black particles have failed to satisfy such various properties.
Namely, in Japanese Patent Application Laid-Open (KOKAI) Nos. 8-245835(1996) and 10-279667(1998), there are described the silica particles whose surface is treated with silane coupling agent or silicone oil. However, when the silica particles are used in semiconductor sealing materials, since some of the silanol groups thereof still remain unreacted with the silane coupling agent, the obtained semiconductor sealing materials show a high water absorption property, resulting in problems such as occurrence of cracks upon soldering. Also, since black pigments such as carbon black must be separately added to binder resins, the obtained semiconductor sealing materials tend to be deteriorated in flowability and electrical resistance.
Further, in Japanese Patent Application Laid-Open (KOKAI) No. 11-43320(1999), it is described that the silica particles previously heated in a temperature range of 100 to 1,000° C. and then treated with the silane coupling agent are used as particles for semiconductor sealing materials. Although the thus treated silica particles exhibit a low water absorption property because of a less content of residual silanol groups, it is required to separately add the black pigments such as carbon black to binder resins, so that the obtained semiconductor sealing materials tend to be deteriorated in flowability and electrical resistance.
Also, in Japanese Patent Application Laid-Open (KOKAI) Nos. 2001-19833, 2001-69268, 2001-247747 and 2001-329146, it is described the control of the maximum particle diameter of the carbon black particles and/or silica particles added to resin compositions. However, since the carbon black particles and the silica particles are separately added to the binder resins, the obtained semiconductor sealing materials show a low electrical resistance.
As a result of the present inventors' earnest studies for solving the above problems, it has been found that by adhering black pigments onto the surface of extender pigments in an amount of 1 to 100 parts by weight based on 100 parts by weight of the extender pigments, the obtained black composite particles can exhibit high blackness, moisture resistance, fluidity and tinting strength, but also excellent dispersibility in binder resins, and are useful as a component for semiconductor sealing materials. The present invention has been attained on the basis of the finding.